Fuel pump is going out or FPR(fuel pressure regulator)
Fuel injection requires a minimum pressure to work.
Your '90 should have 35psi of pressure at the injectors, there is a schrader valve(like a tires air valve) on the fuel rail to test pressure.
The FPR on the fuel rail is hooked to the Return Fuel line, when engine is off it is closed and holds pressure in the system.
The Fuel pump in the gas tank has a Check Valve, pump can push fuel out but when pump is off fuel can't come back, past the check valve.
The FPR and Check valve will hold 35psi of pressure for many months, if they are both OK.
Fuel injectors can also leak pressure but that would show different symptoms usually.
With Ford computers there is a safety feature in case a fuel line should break, the fuel pump will only get 2 seconds of power if engine RPMs are 0.
So when you turn on the key the fuel pump runs for 2 seconds and then stops until RPMs are above 400(engine started), then it comes on again.
The 2 seconds of running causes about 10psi of fuel pressure.
If you started with 0psi(pressure leaked out) engine wouldn't start.
If you turn the key on, and then off 3 times you should get up to 30psi and engine would start(you don't have to pump the gas pedal).
If engine lacks power after starting then it could be fuel pump isn't pump as much fuel any more or FPR is stuck wide open.
You can rent fuel pressure gauges or build one.
Last edited by RonD; 07-26-2015 at 09:57 AM.